如何设置Java线程的cpu核心关联？

Question

I searched previous postings on the similar topic but could not find a befitting answer therefore asking this question. Your help in answering it is highly appreciated.

I am aware of setting a process's affinity to a particular CPU core by taskset command in Linux. But I want to set a Java thread's affinity to a particular cpu core so that other threads belonging to the same process can run on all remaining cores. For example if I have a process containing 10 threads with 4-core machine, I would like to reserve core-1 for a thread and let remaining 9 threads run on remaining 3-cores. Can it be done and how?

Thanks Sachin

Answer 1

Say 2241 is the pid of your java process. Run:

jstack 2241

This gives you a list of threads. Find yours there and note the nid field. Say nid=0x8e9, which converts to base 10 as 2281. Then run:

taskset -p -c 0 2281

Done.

Answer 2

Unfortunately, you cannot assign Java Threads to a specific core. What you can do, however, is set Thread Priorities to prioritize the threads (assuming that this would accomplish the same thing)

Alternatively, you could use JNI, but that would be completely overkill.

Answer 3

Remember the Java application that your running is actually running in a JVM which is in turn running on the OS. For you to be able to directly interact with the CPU you'd need a low level programming language (eg C).

As suggested in another answer you can use JNI to interact with lower level language (like C) to do what you want however you'd have to delegate concurrency (threads managed within that lower level langaguge) to it...

Answer 4

You can do that in plain Java using JNA. There is no need to use taskset. Just remember that thread affinity is pointless unless you have previously isolated the core from kernel/user threads and hardware interrupts. I am affiliated with Coral Blocks which has developed CoralThreads which does exactly that.